yadā hi sarvākhyātānuvartinī karotidhātuvācyā puruṣavyāpārarūpā bhāvanā avagatā bhavati, tadā tadviśeṣāḥ sāmānyākhyātavyatiriktaśabdaviśeṣavācyāḥ vidhipratiṣedhabhūtabhaviṣyadvartamānādayaḥ pratīyante. pacati, apākṣīt, pakṣyati, pacet, na pacet iti (TV ad 184.108.40.206, p. 378).
When indeed the bhāvanā –which has the form of a human activity, can be expressed by the verbal root “to do” [and] is present in all finite verbal forms– is understood, then optative (lit. prescriptions and prohibitions), past, future, present etc. –which are expressed by a certain word (i.e., their specific verbal ending) distinct from the general finite verbal ending [and] are its (the bhāvanā's) characteristics– are [also] understood. For instance, “he cooks”, “he cooked”, “he will cook”, “he should cook”, “he should not cook”.